EARTH'S CORONA, a halo of hydro
gen, flares some 16,000 miles into
space in a 15-second ultraviolet
photograph made through a lithium
fluoride filter. Blue, red, green, and
gold represent increasing concentra
tions of the gas. Longer exposures
show that the geocorona extends to
100,000 miles. Breakdown of water
vapor from the oceans sends hydrogen
drifting far above the planet, while
heavier oxygen remains closer to the
surface. Many scientists now believe
that the separation of water vapor in
to its two elements, rather than photo
synthesis in plants, may be the major
source of the earth's oxygen.
Dr. George R. Carruthers of the
Naval Research Laboratory in Wash
ington, D. C., developed the electronic
camera that registers only ultraviolet
light. Here it rests in the shadow of
the lunar module (below), safe from
damaging heat. Astronaut Charles M.
Duke, Jr., stands between the module
and the lunar Rover. In 180 exposures
the camera recorded not only earth's
atmosphere, but also distant stars, the
solar wind, and possibly intergalactic
hydrogen, whose presence, some scien
tists believe, would increase the
known mass of the universe tenfold.
JOHNW. YOUNG(ABOVE);NASA
859